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Статті в журналах з теми "Effort inertiel du fluide"
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Zhao, Wu, Quan Bin Zhang, Wei Tao Jia, and Zhan Qi Hu. "Influence on BTA Boring Bar Transverse Vibration Considering Inner Cutting Fluid Velocity and Axial Force." Advanced Materials Research 887-888 (February 2014): 1215–18. http://dx.doi.org/10.4028/www.scientific.net/amr.887-888.1215.
Повний текст джерелаАнотація:
A new simulation model on frequency is proposed, to analyze mutual relationship between intrinsic frequency and other factors in system. The study is mainly focused on the axial press effect, inner cutting fluid velocity and its Coriolis inertia effects acting on boring bar. The whole system is assumed to conform to the continuous equal span beam model synthesized with liquid-solid coupling vibration model inner the work and Timoshenko beam model outer the work. Simulations show that system vibration frequency is determined by mechanical properties, axial force, inner cutting fluid velocity and density. Three aspects influence BTA boring bar lateral vibration considering inner cutting fluid velocity and axial force, who are transverse inertial mass, inertia and self-excited vibration on the bar. Inner flowing of the cutting fluids also lead to instability on bar.
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Kim, Uihwan, Joo-Yong Kwon, Taehoon Kim, and Younghak Cho. "Particle Focusing in a Straight Microchannel with Non-Rectangular Cross-Section." Micromachines 13, no. 2 (January 20, 2022): 151. http://dx.doi.org/10.3390/mi13020151.
Повний текст джерелаАнотація:
Recently, studies on particle behavior under Newtonian and non-Newtonian fluids in microchannel have attracted considerable attention because particles and cells of interest can be manipulated and separated from biological samples without any external force. In this paper, two kinds of microchannels with non-rectangular cross-section were fabricated using basic MEMS processes (photolithography, reactive ion etching and anisotropy wet etching), plasma bonding and self-alignment between two PDMS structures. They were used to achieve the experiments for inertial and elasto-inertial particle focusing under Newtonian and non-Newtonian fluids. The particle behavior was compared and investigated for different flow rates and particle size in the microchannel with rhombic and equilateral hexagonal cross section. We also investigated the influence of Newtonian fluid and viscoelastic fluid on particle migration in both microchannels through the numerical simulation. The experimental results showed the multi-line particle focusing in Newtonian fluid over a wide range of flow rates, but the single-line particle focusing was formed in the centerline under non-Newtonian fluid. The tighter particle focusing appeared under non-Newtonian fluid in the microchannel with equilateral hexagonal cross-section than in the microchannel with rhombic cross section because of the effect of an obtuse angle. It revealed that particles suspended in the channel are likely to drift toward a channel center due to a negative net elasto-inertial force throughout the cross-sectional area. Simulation results support the present experimental observation that the viscoelastic fluid in the microchannel with rhombic and equilateral hexagonal cross-section significantly influences on the particle migration toward the channel center owing to coupled effect of inertia and elasticity.
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Kwon, Joo-Yong, Taehoon Kim, Jungwoo Kim, and Younghak Cho. "Particle Focusing under Newtonian and Viscoelastic Flow in a Straight Rhombic Microchannel." Micromachines 11, no. 11 (November 11, 2020): 998. http://dx.doi.org/10.3390/mi11110998.
Повний текст джерелаАнотація:
Particle behavior in viscoelastic fluids has attracted considerable attention in recent years. In viscoelastic fluids, as opposed to Newtonian fluids, particle focusing can be simply realized in a microchannel without any external forces or complex structures. In this study, a polydimethylsiloxane (PDMS) microchannel with a rhombic cross-sectional shape was fabricated to experimentally investigate the behavior of inertial and elasto-inertial particles. Particle migration and behavior in Newtonian and non-Newtonian fluids were compared with respect to the flow rate and particle size to investigate their effect on the particle focusing position and focusing width. The PDMS rhombic microchannel was fabricated using basic microelectromechanical systems (MEMS) processes. The experimental results showed that single-line particle focusing was formed along the centerline of the microchannel in the non-Newtonian fluid, unlike the double-line particle focusing in the Newtonian fluid over a wide range of flow rates. Numerical simulation using the same flow conditions as in the experiments revealed that the particles suspended in the channel tend to drift toward the center of the channel owing to the negative net force throughout the cross-sectional area. This supports the experimental observation that the viscoelastic fluid in the rhombic microchannel significantly influences particle migration toward the channel center without any external force owing to coupling between the inertia and elasticity.
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Li, Gaojin, Gareth H. McKinley, and Arezoo M. Ardekani. "Dynamics of particle migration in channel flow of viscoelastic fluids." Journal of Fluid Mechanics 785 (November 23, 2015): 486–505. http://dx.doi.org/10.1017/jfm.2015.619.
Повний текст джерелаАнотація:
The migration of a sphere in the pressure-driven channel flow of a viscoelastic fluid is studied numerically. The effects of inertia, elasticity, shear-thinning viscosity, secondary flows and the blockage ratio are considered by conducting fully resolved direct numerical simulations over a wide range of parameters. In a Newtonian fluid in the presence of inertial effects, the particle moves away from the channel centreline. The elastic effects, however, drive the particle towards the channel centreline. The equilibrium position depends on the interplay between the elastic and inertial effects. Particle focusing at the centreline occurs in flows with strong elasticity and weak inertia. Both shear-thinning effects and secondary flows tend to move the particle away from the channel centreline. The effect is more pronounced as inertia and elasticity effects increase. A scaling analysis is used to explain these different effects. Besides the particle migration, particle-induced fluid transport and particle migration during flow start-up are also considered. Inertial effects, shear-thinning behaviour, and secondary flows are all found to enhance the effective fluid transport normal to the flow direction. Due to the oscillation in fluid velocity and strong normal stress differences that develop during flow start-up, the particle has a larger transient migration velocity, which may be potentially used to accelerate the particle focusing.
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Mei, Renwei, and Ronald J. Adrian. "Effect of Reynolds Number on Isotropic Turbulent Dispersion." Journal of Fluids Engineering 117, no. 3 (September 1, 1995): 402–9. http://dx.doi.org/10.1115/1.2817276.
Повний текст джерелаАнотація:
The influence of the spatio-temporal structure of isotropic turbulence on the dispersion of fluid and particles with inertia is investigated. The spatial structure is represented by an extended von Ka´rma´n energy spectrum model which includes an inertial sub-range and allows evaluation of the effect of the turbulence Reynolds number, Reλ. Dispersion of fluid is analyzed using four different models for the Eulerian temporal auto-correlation function D(τ). The fluid diffusivity, normalized by the integral length scale L11 and the root-mean-square turbulent velocity u0, depends on Reλ. The parameter cE = T0u0/L11, in which T0 is the Eulerian integral time scale, has commonly been assumed to be constant. It is shown that cE strongly affects the value of the fluid diffusivity. The dispersion of a particle with finite inertia and finite settling velocity is analyzed for a large range of a particle inertia and settling velocity. Particle turbulence intensity and diffusivity are influenced strongly by turbulence structure.
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Jayaram, Rohith, Yucheng Jie, Lihao Zhao, and Helge I. Andersson. "Dynamics of inertial spheroids in a decaying Taylor–Green vortex flow." Physics of Fluids 35, no. 3 (March 2023): 033326. http://dx.doi.org/10.1063/5.0138125.
Повний текст джерелаАнотація:
Inertial spheroids, prolates and oblates, are studied in a decaying Taylor–Green vortex (TGV) flow, wherein the flow gradually evolves from laminar anisotropic large-scale structures to turbulence-like isotropic Kolmogorov-type vortices. Along with particle clustering and its mechanisms, preferential rotation and alignment of the spheroids with the local fluid vorticity are examined. Particle inertia is classified by a nominal Stokes number [Formula: see text] which to first-order aims to eliminate the shape effect. The clustering varies with time and peaks when the physically relevant flow and particle time scales are of the same order. Low inertial ([Formula: see text]) spheroids are subjected to the centrifuging mechanism, thereby residing in stronger strain-rate regions, while high inertial ([Formula: see text]) spheroids lag the flow evolution and modestly sample strain-rate regions. Contrary to the expectations, however, spheroids reside in high strain-rate regions when the particle and flow time scales are comparable due to the dynamic interactions between the particles and the evolving flow scales. Moderately inertial ([Formula: see text]) prolates preferentially spin and oblates tumble throughout the qualitatively different stages of the TGV flow. These preferential modes of rotation correlate with parallel and perpendicular alignments of prolate and oblate spheroids, respectively, with the local fluid vorticity. However, for high inertial spheroids preferential rotation and alignment are decorrelated due to a memory effect, i.e., inertial particles require longer time to adjust to the local fluid flow. This memory effect is not only due to high particle inertia, as in statistically steady turbulence, but also caused by the continuously evolving TGV flow scales.
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Salazar, Juan P. L. C., and Lance R. Collins. "Inertial particle relative velocity statistics in homogeneous isotropic turbulence." Journal of Fluid Mechanics 696 (March 5, 2012): 45–66. http://dx.doi.org/10.1017/jfm.2012.2.
Повний текст джерелаАнотація:
AbstractIn the present study, we investigate the scaling of relative velocity structure functions, of order two and higher, for inertial particles, both in the dissipation range and the inertial subrange using direct numerical simulations (DNS). Within the inertial subrange our findings show that contrary to the well-known attenuation in the tails of the one-point acceleration probability density function (p.d.f.) with increasing inertia (Bec et al., J. Fluid Mech., vol. 550, 2006, pp. 349–358), the opposite occurs with the velocity structure function at sufficiently large Stokes numbers. We observe reduced scaling exponents for the structure function when compared to those of the fluid, and correspondingly broader p.d.f.s, similar to what occurs with a passive scalar. DNS allows us to isolate the two effects of inertia, namely biased sampling of the velocity field, a result of preferential concentration, and filtering, i.e. the tendency for the inertial particle velocity to attenuate the velocity fluctuations in the fluid. By isolating these effects, we show that sampling is playing the dominant role for low-order moments of the structure function, whereas filtering accounts for most of the scaling behaviour observed with the higher-order structure functions in the inertial subrange. In the dissipation range, we see evidence of so-called ‘crossing trajectories’, the ‘sling effect’ or ‘caustics’, and find good agreement with the theory put forth by Wilkinson et al. (Phys. Rev. Lett., vol. 97, 2006, 048501) and Falkovich & Pumir (J. Atmos. Sci., vol. 64, 2007, 4497) for Stokes numbers greater than 0.5. We also look at the scaling exponents within the context of the model proposed by Bec et al. (J. Fluid Mech., vol. 646, 2010, pp. 527–536). Another interesting finding is that inertial particles at low Stokes numbers sample regions of higher kinetic energy than the fluid particle field, the converse occurring at high Stokes numbers. The trend at low Stokes numbers is predicted by the theory of Chun et al. (J. Fluid Mech., vol. 536, 2005, 219–251). This work is relevant to modelling the particle collision rate (Sundaram & Collins, J. Fluid Mech., vol. 335, 1997, pp. 75–109), and highlights the interesting array of phenomena induced by inertia.
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Meng, Fan-Ming, Sheng Yang, Zhi-Tao Cheng, Yong Zheng, and Bin Wang. "Effect of fluid inertia force on thermal elastohydrodynamic lubrication of elliptic contact." Mechanics & Industry 22 (2021): 13. http://dx.doi.org/10.1051/meca/2021010.
Повний текст джерелаАнотація:
A non-Newtonian thermal elastohydrodynamic lubrication (TEHL) model for the elliptic contact is established, into which the inertia forces of the lubricant is incorporated. In doing so, the film pressure and film temperature are solved using the associated equations. Meanwhile, the elastic deformation is calculated with the discrete convolution and fast Fourier transform (DC-FFT) method. A film thickness experiment is conducted to validate the TEHL model considering the inertia forces. Further, effects of the inertia forces on the TEHL performances are studied at different operation conditions. The results show that when the inertia forces are considered, the central and minimum film thicknesses increase and film temperature near the inlet increases obviously. Moreover, the inertial solution of the central film thickness is closer to the experimental result compared with its inertialess value.
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Блинков, Юрий Анатольевич, Лев Ильич Могилевич, Виктор Сергеевич Попов, and Елизавета Викторовна Попова. "Evolution of solitary hydroelastic strain waves in two coaxial cylindrical shells with the Schamel physical nonlinearity." Computational Continuum Mechanics 16, no. 4 (December 1, 2023): 430–44. http://dx.doi.org/10.7242/1999-6691/2023.16.4.36.
Повний текст джерелаАнотація:
The paper considers the formulation and solution of the hydroelasticity problem for studying wave processes in the system of two coaxial shells containing fluids in the annular gap between them and in the inner shell. We investigate the axisymmetric case for Kirchhoff–Lave type shells whose material obeys a physical law with a fractional exponent of the nonlinear term (Schamel nonlinearity). The dynamics of fluids in the shells is considered within the framework of the incompressible viscous Newtonian fluid model. The derivation of the Schamel nonlinear equations of shell dynamics makes it possible to develop a mathematical formulation of the problem, which includes the obtained equations, the dynamics equations of two shells, the fluid dynamics equations and the boundary conditions at the shell-fluid interfaces and at the flow symmetry axis. The asymptotic analysis of the problem is performed using perturbation techniques, and the system of two generalized Schamel equations is obtained. This system describes the evolution of nonlinear solitary hydroelastic strain waves in the coaxial shells filled with viscous fluids, taking into account the inertia of the fluid motion. In order to determine the fluid stress at the shell-fluid interfaces, we perform linearization of the fluid dynamics equations for fluids in the annular gap and in the inner shell. The linearized equations are solved by the iterative method. The inertial terms are excluded from the equations in the first iteration, while, in the second iteration, these are the values found in the first iteration. A numerical solution of the system of nonlinear evolution equations is obtained by applying a new difference scheme developed using the Gröbner basis technique. Computational experiments are performed to investigate the effect of fluid viscosity and the inertia of fluid motion in the shells on the wave process. In the absence of fluids in the inner shell, the results of calculations demonstrate that the strain waves in the shells during elastic interactions do not change their shape and amplitude, i.e., they are solitons. The presence of viscous fluid in the inner shell leads to attenuation of the wave process.
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Behera, Nalinikanta, Shubhadeep Mandal, and Suman Chakraborty. "Electrohydrodynamic settling of drop in uniform electric field: beyond Stokes flow regime." Journal of Fluid Mechanics 881 (October 24, 2019): 498–523. http://dx.doi.org/10.1017/jfm.2019.744.
Повний текст джерелаАнотація:
The electrohydrodynamics of a weakly conducting buoyant drop under the combined influence of gravity and a uniform electric field is studied computationally, focusing on the inertia-dominated regime. Numerical simulations are performed for both perfectly dielectric and leaky dielectric drops over a wide range of dimensionless parameters to explore the interplay of fluid inertia and electrical stress to govern the drop shape and charge convection. For perfectly dielectric drops, the fluid inertia alters the drop shape and the deformation behaviour of the drop follows a non-monotonic path. The drop shape at steady state exhibits the transition from oblate to prolate shape on increasing the electric field strength, in sharp contrast to the cases concerning the Stokes flow regime. Similar behaviour is also obtained for leaky dielectric drops for certain fluid properties. For leaky dielectric drops, the fluid inertia also affects the convective transport of charges at the drop surface and thereby alters the drop dynamics. Unlike the Stokes flow regime, where surface charge convection has little effect on the settling speed, the same modifies the drop settling speed quite significantly in the finite inertial regime depending on the combination of electrical conductivity ratio and permittivity ratio. For oblate drops at low capillary number, charge convection alters drop shape, while keeping the nature of deformation unaltered. However, for relatively large capillary number, the oblate drop transforms into a dimpled shape due to charge convection. For all cases, an interesting fact is noticed that under the combined action of electric and inertial forces, the resultant deformation is less than the summation of the deformations caused by individual effects, when inertial effects are strong. These results are likely to provide deep insights into the interplay of various nonlinearities towards altering electrohydrodynamic settling of drops and bubbles.
Дисертації з теми "Effort inertiel du fluide"
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Pérez, Tamarez Julio. "Etude numérique de voilures souples en milieu fluide : aide à la propulsion." Electronic Thesis or Diss., Normandie, 2025. http://www.theses.fr/2025NORMIR04.
Повний текст джерелаАнотація:
Le comportement d’une membrane sans épaisseur placée dans un écoulement unidirectionnel et irrotationnel a été analysé à l’aide de simulations numériques. La portance, la poussée et les forces inertielles ont été calculées en fonction de la distribution de pression au-dessus et en dessous de la membrane en utilisant la méthode des tourbillons. Laréponse du solide a été calculée à partir des hypothèses de grands déplacements en appliquant la mécanique lagrangienne à l’aide du logiciel ANSYS APDL, avec une résolution temporelle basée sur la méthode HHT-α, où la méthode de Newton-Raphson a été utilisée pour résoudre les aspects non linéaires.L’interaction fluide-solide a été obtenue par un échange explicite de données entre le code de simulation de fluide et le modèle structurel, en se basant sur les conditions cinétiques et dynamiques à la frontière d’interface, tout en prenant en compte le critère de l’échantillonnage de Nyquist-Shannon ainsi que les conditions de Courant-Friedrichs-Lewy. Une nouvelle décomposition matricielle des efforts hydrodynamiques a été appliquée avec succès, permettant de quantifier l’influence des composantes des efforts hydrodynamiques, démontrant ainsi la valeur instantanée des efforts inertiels du fluide. Une étude de l’efficacité propulsive du système en fonction des fréquences d’oscillation, des propriétés mécaniques du solide déformable, et des configurations mécaniques du système a été réalisée afin de déterminer la propulsion optimaleThe behavior of a thicknessless membrane placed in a unidirectional and irrotational flow is analyzed using numerical simulation. The lift, thrust and inertial forces were calculated based on the pressure distribution over and under the membrane using the Vortex Method. The response of the solid was calculated based on the large displacement hypothesis using the Timoshenko beam theory and total Lagrangian formulation in ANSYS APDL, with time resolution based on HHT-α method, where the Newton-Raphson method was applied to resolve non-linear aspects.Fluid-solid interaction was achieved through explicit data exchange between the fluid simulation code and the structural model based on the kinetic and dynamic conditions at the interface boundary and paying special attention to the Nyquist–Shannon criteria and the Courant-Friedrich-Levy's conditions. A new matricial decomposition of hydrodynamic efforts was successfully applied, allowing us to quantify the influence of the inertial force component in the flow and demonstrate the instant value of the added inertia. A study of the thrust in relation to the beating frequencies, the mechanical properties of the deformable solid and the system's mechanical configurations was carried out to find the best propulsion conditions
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Marouche, Mohamed. "Hydrodynamique d'un système d'agitation en fluide viscoplastique et en régime laminaire inertiel." Toulouse, INPT, 2002. http://www.theses.fr/2002INPT011H.
Повний текст джерелаАнотація:
L'hydrodynamique d'un système d'agitation est très dépendante, quantitativement et qualitativement, de la nature rhéologique des fluides impliqués dans le procédé. Dans ce travail, on étudie le cas de fluides viscoplastiques très visqueux dans un système d'agitation classique: une cuve cylindrique et un agitateur ancre. Le cas du ruban hélicoi͏̈dal est également abordé. On s'intéresse aux écoulements laminaires, incompressibles et isothermes. La première partie de ce travail est consacrée à une approche numérique effectuée à l'aide d'un code industriel ('Fluent'). Le seuil d'écoulement lié au comportement viscoplastique est modélisé par une loi théorique de Bingham. Dans un premier temps, une étude sur l'écoulement de Couette entre cylindres coaxiaux permet de tester la validité et les limites des modèles adoptés pour approcher cette loi. On développe également une étude analytique de la puissance consommée et de la validité d'une extension de la loi de Metzner et Otto. Les résultats obtenus sont ensuite utilisés pour réaliser l'étude du système d'agitation en géométrie bi- puis tri-dimensionnelle. Les champs de vitesse sont analysés. On montre que l'existence d'un seuil, caractérisé par le nombre de Hedström, peut conduire à une quasi-immobilisation de larges zones à l'intérieur du système d'agitation. Les effets croisés de l'inertie et de la viscoplasticité sont étudiés. Une application au mélange est proposée. La deuxième partie de ce travail est consacrée à une approche expérimentale. Des mesures du champ de vitesse dans une section horizontale de la cuve ont été réalisées par vélocimétrie par images de particules (PIV). L'étude a été faite en fluide newtonien (solutions de glucose) et en fluide viscoplastique (solutions de Carbopol). Des glissements à la paroi ont été observés et annulés par l'adjonction de rugosités sur la cuve. Une comparaison avec les résultats numériques est ensuite effectuée et analysée.
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Bentata, Omar. "Étude expérimentale d'un anneau tourbillonnaire en fluide newtonien et non newtonien en régime faiblement inertiel." Phd thesis, Toulouse, INPT, 2013. http://oatao.univ-toulouse.fr/9703/1/bentata.pdf.
Повний текст джерелаАнотація:
Cette thèse est une étude expérimentale de la formation et de la maturation d’un anneau tourbillonnaire. Elle porte sur les écoulements faiblement inertiels (Reynolds : 5 à 500) en fluide newtonien puis non newtonien. Les anneaux sont générés par un système cylindre-piston. Ils sont analysés par visualisation et par vélocimétrie par images de particules (PIV). La dynamique en fluide newtonien à faible nombre de Reynolds se révèle plus complexe que celle à grands Reynolds avec l’apparition d’un anneau secondaire contrarotatif. Les résultats obtenus en fluide rhéofluidifiant montrent l’influence de l’indice de comportement ainsi que les zones de comportement rhéofluidifiant et newtonien. Les explorations en fluides viscoplastique et viscoélastique montrent la formation d’un ou plusieurs anneaux secondaires contrarotatifs, qui diffèrent dans leur formation et leur dynamique des anneaux observés en fluide newtonien et que l’on associe aux propriétés physiques intrinsèques du fluide.
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Letessier, Dylan. "Chute en régime inertiel de cylindres isolés ou en groupes dans une cellule mince." Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSEP030.
Повний текст джерелаАнотація:
Afin d'améliorer notre compréhension du comportement de corps solides anisotropes en mouvement dans un liquide en régime inertiel, nous avons étudié la chute d'un groupe de cylindres de taille finie évoluant en milieu confiné. L'utilisation d'une cellule de faible entrefer, qui laisse trois degrés de liberté aux cylindres, permet de suivre par imagerie rapide leur comportement. Dans ce but, un dispositif expérimental pré-existant a été amélioré, afin de permettre notamment d'introduire un contre-écoulement, ainsi qu'un système permettant la libération coordonnée de cylindres en groupe. En complément, les champs de vitesses dans le liquide, intégrés sur l’épaisseur de la cellule, peuvent être obtenus par PIV ombroscopique. En variant les longueurs et masses volumiques des cylindres toujours dans de l'eau, nous avons analysé l'impact des rapports de forme, des rapports de densité et du nombre d'Archimède sur la cinématique observée. Dans un premier temps, nous avons analysé l'influence de ces paramètres sur les caractéristiques du comportement d'un cylindre seul, isolé en milieu confiné. Ceci nous a conduit à une modélisation approfondie des forces en jeu et de leur interaction avec le fluide environnant. Cette modélisation s'est appuyée sur le formalisme des équations généralisées de Kelvin-Kirchhoff auxquelles nous avons ajouté des forces de traînée et de portance, mais également une force d'histoire qui permet de fermer le modèle sur une large gamme de paramètres. Nous montrons que les larges amplitudes des fluctuations conduisent à une contribution moyenne de la force inertielle couplant les translation et rotation du cylindre qui impacte sa vitesse moyenne de chute. Ceci nous a également permis d'avoir une prédiction de la fréquence d'oscillation. La présence d'un contre-écoulement ascendant, n'affecte pas sensiblement la vitesse relative par rapport au fluide et la fréquence d'oscillation du corps. Cependant, elle peut conduire à une re-stabilisation des trajectoires, dans certaines gammes de paramètres. Dans un second temps, notre attention s'est portée vers le comportement collectif d'un groupe de cylindres en chute libre en régime inertiel. Les conditions de lâchers étaient similaires d'un essai à l'autre, incluant le temps de lâcher et l'arrangement initial ; seul le nombre de cylindres, la masse volumique des cylindres et leur rapport de forme étaient variables. En observant ces groupes suffisamment loin du point d'injection, nous avons montré qu'ils évoluaient avec des vitesses verticales de chute constantes, occupaient une surface constante et présentaient des structures internes complexes fortement dépendantes des paramètres de contrôle. La structure est constituée d'objets regroupant plusieurs cylindres, qui interagissent, coalescent ou se fragmentent. Nous avons aussi mis en évidence la présence d’hétérogénéités importantes au sein du groupe, avec l’apparition de zones plus concentrées comprenant un plus grand nombre d'objets, plongeant plus vite dans le liquide, que nous avons appelé "coulées". L'analyse détaillée des vitesses des différents objets nous a permis de montrer que ceux-ci présentent des distributions statistiques comparables. Un modèle simple équilibrant traînée et flottabilité considérant le groupe comme un objet unique homogénéisé nous a permis d'obtenir une prédiction de la vitesse de chute du groupe, une fois son rayon équivalent connu. L'analyse des écarts-types des fluctuations de vitesse des objets au sein du groupe nous a permis de fournir des lois d'échelle prédictives basées sur deux ingrédients différents dans les directions horizontales et verticales, respectivement : la mobilité propre du corps isolé, caractérisée par sa fréquence d'oscillation et de lâcher tourbillonnaire, et les entraînements par les sillages et les coulées, moteur des fluctuations verticales, pris en compte par une concentration caractéristique du nuageIn order to improve our understanding of the behavior of anisotropic solid bodies in motion within a liquid under inertial conditions, we investigated the fall of a group of finite-sized cylinders in a confined environment. The use of a thin-gap cell, reducing the motion of the cylinders to three degrees of freedom, allowed us to track their behavior through high-speed imaging. To achieve this, an existing experimental setup was improved, by introducing in particular a counterflow and a system enabling the coordinated release of cylinders in a group. In addition to high-resolution cameras, seeding of the liquid was performed to enable the determination of the liquid velocity field, integrated across the thickness of the cell, using PIV shadowgraphy. By varying the lengths and densities of the cylinders, released in water, we analyzed the impact of the aspect ratios, the density ratio, and the Archimedes number of the cylinders on the observed kinematics. Initially, we examined the influence of these parameters on the behavior characteristics of a single cylinder, isolated in a confined medium. This led to a comprehensive modeling of the forces at play and their interaction with the surrounding fluid. The modeling relied on the Kelvin-Kirchhoff generalized equations, to which we added drag and lift forces, as well as a history force to close the model over a wide range of parameters. We demonstrated that the large amplitudes of fluctuations contribute to an average inertial force coupling the translation and rotation of the cylinder, affecting its mean fall velocity. This also allowed us to predict the oscillation frequency of the fluttering motion. The presence of an upward counterflow does not significantly affect the cylinder velocity relative to the fluid and the oscillation frequency. However, it may lead to trajectory restabilization under certain parameter ranges. In a second phase, we focus our attention to the collective behavior of a group of freely falling cylinders under inertial conditions. Release conditions were consistent across experiments, including release time and initial packing; only the number of cylinders, cylinder density, and aspect ratio varied. Observing these groups sufficiently far from the injection point, we demonstrated that the groups evolved with constant vertical falling velocities, occupied a constant surface, and featured complex internal structures highly dependent on control parameters. These structures consisted of objects grouping several cylinders, interacting, coalescing, or fragmenting. We also highlighted significant heterogeneities within the group, with the emergence of more concentrated areas containing a greater number of objects, plunging faster into the liquid, which we referred to as "streams". Detailed analysis of the velocities displayed by the different objects allowed us to show that they presented comparable statistical distributions. A simple model balancing drag and buoyancy, considering the group as a homogenized single object, allowed us to predict the group's fall velocity once its equivalent radius was known. The analysis of the standard deviations of velocity fluctuations of objects within the group allowed us to provide predictive scaling laws based on two different ingredients in the horizontal and vertical directions, respectively: the proper mobility of the isolated body, characterized by its frequency of oscillation and of vortex shedding, and the entrainment by the wakes and streams, driving the vertical fluctuations, accounted for by a characteristic concentration for the group
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Yahiaoui, Samir. "Transport de petites particules par un écoulement de fluide visqueux." Paris 6, 2008. http://www.theses.fr/2008PA066384.
Повний текст джерелаАнотація:
Ce mémoire contribue à l'étude des interactions hydrodynamiques particules-paroi dans un écoulement à faible nombre de Reynolds. Divers écoulements de Stokes axisymétriques sont calculés pour une sphère proche d'une paroi plane. On utilise ensuite les techniques de perturbation pour déterminer les forces hydrodynamiques : la force de traînée visqueuse inertielle et instationnaire pour le mouvement d'une sphère normal à une paroi plane, la force de portance pour une sphère en mouvement parallèle à une paroi dans différents écoulements ambiant, sans aucune restriction sur la distance séparant la sphère et la paroi. En régime de lubrification, on apporte également des corrections aux approximations des vitesses et pression du fluide dans le cas où la sphère sédimente perpendiculairement à la paroiThis work contributes to the study of hydrodynamic interactions between particles and wall in low Reynolds number fluid flow. Various axisymetric Stokes flows are calculated for a sphere near a plane wall. Perturbation techniques are then used to determine hydrodynamic forces, namely the viscous inertial unsteady drag force for the motion of a sphere normal to a plane wall and the lift on a sphere moving parallel to a plane wall in various ambient flow fields; regardless of the sphere to wall distance. In the lubrication regime, corrections are also derived for the approximated fluid velocity and pressure around a sphere settling normal to a wall
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Melot, Vincent. "Hydrodynamique instationnaire d'un cylindre sous choc." Phd thesis, Université de Nantes, 2006. http://tel.archives-ouvertes.fr/tel-00124063.
Повний текст джерелаАнотація:
Ce travail présente une étude analytique, numérique et expérimentale de l'hydrodynamique d'un cylindre soumis à un choc sinus. L'étude analytique consiste à développer un modèle général permettant de prédire les forces et la répartition de pressions sur le cylindre soumis à un mouvement transitoire quelconque dans un fluide visqueux bidimensionel. La simulation numérique s'attache à la modélisation en maillage mobile d'un cylindre évoluant dans un domaine fluide infini bidimensionel sous le code généraliste STAR-CD. Un dispositif expérimental avec la chaîne de mesure associée est conçu permettant d'imposer différents types de mouvements (choc sinus, mouvement oscillatoire entretenu) à un cylindre baignant dans un bassin. Ces trois approches complémentaires montrent que l'écoulement est régi par deux nombres adimensionnels : le nombre de Stokes, Beta, et le nombre de Keulegan-Carpenter, KC. Beta mesure le rapport entre le temps de diffusion visqueuse et le temps caractéristique du choc et KC le rapport entre le déplacement maximum du corps et son diamètre. Dans le cas où Beta est très grand (fluide parfait), la force sur le cylindre est régie par l'effet inertiel quelque soit KC. A petit KC, la pression est contrôlée uniquement par l'effet inertiel alors que pour des grands KC, un effet d'advection vient s'ajouter. A Beta modéré et pour des petites valeurs de KC, la force et la pression subissent trois effets : un effet d'inertie, d'histoires et de traînée. Pour des grandes valeurs de KC, l'écoulement devient plus riche : des zones dynamiques de vorticité apparaissent. Elles induisent de fortes fluctuations locales de pression sans modifier la force totale. Ce travail se termine par l'étude d'un cas d'interaction fluide-structure où les outils de prédiction et de simulation développés récédemment sont mis en oeuvre. Les phénomènes d'inertie, de trainée et les effets d'histoire apparaissent simultanément et sont couplés avec le mouvement du cylindre.
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Chen, Xiaodong. "Fluid-Structure Interaction Modeling of Epithelial Cell Deformation during Microbubble Flows in Compliant Airways." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1332208862.
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Sarkis, Bruno. "Étude numérique de la relaxation de capsules confinées par couplage des méthodes Volumes Finis - Éléments Finis via la méthode des frontières immergées IBM : influence de l'inertie et du degré de confinement." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS184/document.
Повний текст джерелаАнотація:
Les capsules, formées d’une goutte protégée par une membrane élastique, sont très présentes naturellement et dans diverses applications industrielles, mais peu d’études ont exploré les phénomènes transitoires de leur relaxation. L’objectif est d’étudier l’influence de l’inertie et du confinement sur la relaxation d’une capsule sphérique (1) pré-déformée en ellipsoïde et relâchée dans un canal carré où le fluide est au repos, (2) sous écoulement dans un canal carré à expansion soudaine (‘marche’). La capsule est modélisée comme un fluide Newtonien dans une membrane hyper-élastique sans épaisseur ni viscosité, et simulée en couplant les méthodes Volumes Finis - Eléments Finis - frontières immergées. Sa relaxation dans un fluide au repos comporte 3 phases : amorçage du mouvement du fluide, phases rapide puis lente de rétraction de la membrane. Trois régimes existent selon le rapport de confinement et le rapport des nombres de Reynolds et capillaire : amortissements pur, critique ou oscillant. Un modèle de Kelvin-Voigt inertiel est proposé pour prédire les temps de réponse et aussi appliqué à une capsule en écoulement dans le canal microfluidique avec marche. La comparaison aux simulations 3D montre sa pertinence aux temps courts de la relaxation. Ces travaux ouvrent la voie à l’étude d’écoulements transitoires de capsules confinées dans des systèmes microfluidiques complexesCapsules, made of a drop protected by an elastic membrane, are widly present in nature and in diverse industrial applications, but few studies have explored the transient phenomena governing their relaxation. The objective of the PhD is to study the influence of inertia and confinement on the relaxation of a spherical capsule (1) pre-deformed into an ellipsoid and released in a square channel where the fluid is quiescent, (2) flowing in a square channel with a sudden expansion (‘step’). The capsule is modeled as a Newtonian fluid in a hyperelastic membrane without thickness or viscosity and is simulated coupling the Finite Volume - Finite Element - Immersed Boundary Methods. Its relaxation in a quiescent fluid exhibits three phases: the initiation of the fluid motion, the rapid and then slow retraction phases of the membrane. Three regimes exist depending on the confinement ratio and the Reynolds to capillary number ratio: pure, critical or oscillating damping. A Kelvin-Voigt inertial model is proposed to predict the response time constants and also applied to a capsule flowing in the microfluidic channel with a step. The comparison to 3D simulations shows its relevance at short relaxation times. This work paves the way to the study of transient flows of capsules confined in microfluidic devices
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Mossaz, Stephane. "Etudes expérimentales et numériques des écoulements inertiels de fluides à seuil autour d'un cylindre." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00721804.
Повний текст джерелаАнотація:
Les écoulements rampants, recirculants et instationnaires d'un fluide viscoplastique autour d'un cylindre ont été étudiés.Numériquement, les morphologies des écoulements, la localisation des zones rigides, les champs de contraintes et pression autour du cylindre ainsi que le coefficient de traînée, ont été déterminés sur un large domaine des nombres de Reynolds et d'Oldroyd.Expérimentalement, les fluides étudiés sont des gels de polymère Carbopol®. Le comportement élastoviscoplastique de ces gels a été modélisé par une loi d'Herschel-Bulkley adaptée. Le montage expérimental conçu et réalisé a été validé par l'étude de l'écoulement d'un fluide newtonien autour d'un cylindre et la mise en place d'une procédure adaptée pour les fluides à seuil.On a pu constater l'influence des conditions d'interface avec l'apparition d'une morphologie de lâchers de tourbillons simultanés et symétriques.
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Ozogul, Hamdullah. "Écoulements de fluides à seuil autour d'un cylindre en milieu confiné : études expérimentale et numérique." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI005/document.
Повний текст джерелаАнотація:
Ce travail de thèse concerne les écoulements de fluides à seuil de contrainte autour d‘un obstacle cylindrique en milieu confiné avec une configuration d‘écoulement de Poiseuille.Expérimentalement, un banc d‘essai permettant d‘obtenir un écoulement en continu dans un circuit fermé a été mis en place. Les régimes d‘écoulement rampant, recirculant et instationnaire périodique ont été étudiés. De nouveaux résultats ont été obtenus avec un fluide newtonien et des solutions de Carbopol, polymère permettant de réaliser des fluides à seuil modèles utilisés en recherche et développement et dans l‘industrie. Une caméra rapide et un éclairage plan laser a servi pour l‘établissement d‘images qui ont ensuite été traitées par PIV. Les champs de vitesses cinématiques, les morphologies d‘écoulement et les paramètres critiques de transitions de régimes ont été déterminés.Numériquement, un modèle viscoplastique basé sur la loi de Herschel-Bulkley régularisée a été utilisé. Des résultats comme les morphologies d‘écoulement, la localisation des zones rigides, les champs de vitesses ont été obtenus. Ceci a permis de comparer les différences entre les effets liés à la nature des gels de Carbopol et la modélisation viscoplastiques. Une étude spécifique sur le glissement à l‘interface fluide-structure a également été réalisée avec l‘utilisation d‘un modèle de lubrification élasto-hydrodynamiqueThe flow of yield stress fluids around a circular cylinder in a confined geometry has been investigated with a Poiseuille flow configuration.Experimentally, a test set-up was built which provides a continuous flow in a closed loop. We studied creeping, recirculating and vortex shedding flow regimes. New results has been realised with a Newtonian fluid and Carbopol solutions, models for yield stress behaviour in laboratory experiments and in industry. A high speed camera and a laser sheet have been used to perform images which are treated by PIV. Kinematic fields, flow morphologies and critical transition parameters have been determined.Numerically, a viscoplastic model based on the regularised Herschel-Bulkley law has been used. Results as flow morphologies, rigid areas and local flow parameters fields have been performed. That allowed us to compare the intrinsic effects of Carbopol solutions and the viscoplastic numerical model. A specific study on the wall slip has also been considered with an elasto-hydrodynamic lubrication model
Частини книг з теми "Effort inertiel du fluide"
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Mohapatra, Dhiren, Rahul Purwar, and Amit Agrawal. "Effect of Viscosity on the Margination of White Blood Cells in an Inertial Flow Microfluidic Channel." In Fluid Mechanics and Fluid Power, Volume 4, 543–51. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-7177-0_44.
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Xi, Heng-Dong, Sheng-Hong Peng, and Yi-Bao Zhang. "Turbulent/Non-turbulent Interface in Water Jet with Polymer Additives." In IUTAM Bookseries, 226–37. Cham: Springer Nature Switzerland, 2024. https://doi.org/10.1007/978-3-031-78151-3_18.
Повний текст джерелаАнотація:
AbstractThe effect of polymer additives on the global entrainment of a turbulent round jet was found to show two distinct regimes: the reduction and enhancement regimes in the near and far fields, respectively. Using time-resolved simultaneous particle image velocimetry and laser-induced fluorescence measurements, we hereby present an experimental study on the local entrainment and engulfment process along the turbulent/non-turbulent interface (TNTI). We find that the local entrainment velocity is augmented in both regimes, due to the contribution from polymer elastic stress and a higher probability for TNTI to visit jet centreline region where the entrainment velocity is larger. In the entrainment reduction regime, the fractal dimension and length of TNTI are smaller compared to the Newtonian case; while those in the enhancement regime are nearly not changed. The difference between the two regimes results from the fact the jet flow decays in the streamwise direction. In the near field, the flow is intense enough to substantially stretch polymers, which results in a redistribution of energy among different scales and a steeper decay of energy in the inertial range. However, in the far field, the stretching of the polymer and in turn the feedback of polymers is not strong enough to alter the inertial range scaling of the energy spectrum. Moreover, our study reveals although more ambient fluid is engulfed into the turbulent region due to the augmented large scale motion by polymers, engulfment is still not the major contribution to the entrainment in polymer-laden jet, which is similar to the case in Newtonian jet.
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Fede, Pascal, and Olivier Simonin. "Effect of Particle-Particle Collisions on the Spatial Distribution of Inertial Particles Suspended in Homogeneous Isotropic Turbulent Flows." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 119–25. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-14139-3_14.
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T. Kajero, Olumayowa, Mukhtar Abdulkadir, Lokman Abdulkareem, and Barry James Azzopardi. "The Effect of Liquid Viscosity on the Rise Velocity of Taylor Bubbles in Small Diameter Bubble Column." In Vortex Dynamics Theories and Applications. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.92754.
Повний текст джерелаАнотація:
The rise velocity of Taylor bubbles in small diameter bubble column was measured via cross-correlation between two planes of time-averaged void fraction data obtained from the electrical capacitance tomography (ECT). This was subsequently compared with the rise velocity obtained from the high-speed camera, manual time series analysis and likewise empirical models. The inertia, viscous and gravitational forces were identified as forces, which could influence the rise velocity. Fluid flow analysis was carried out using slug Reynolds number, Froude number and inverse dimensionless viscosity, which are important dimensionless parameters influencing the rise velocity of Taylor bubbles in different liquid viscosities, with the parameters being functions of the fluid properties and column diameter. It was found that the Froude number decreases with an increase in viscosity with a variation in flow as superficial gas velocity increases with reduction in rise velocity. A dominant effect of viscous and gravitational forces over inertia forces was obtained, which showed an agreement with Stokes law, where drag force is directly proportional to viscosity. Hence, the drag force increases as viscosity increases (5 < 100 < 1000 < 5000 mPa s), leading to a decrease in the rise velocity of Taylor bubbles. It was concluded that the rise velocity of Taylor bubbles decreases with an increase in liquid viscosity and, on the other hand, increases with an increase in superficial gas velocity.
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Singh, Sukhmander, Bhavna Vidhani, Sonia Yogi, Ashish Tyagi, Sanjeev Kumar, and Shravan Kumar Meena. "Plasma Waves and Rayleigh–Taylor Instability: Theory and Application." In Plasma Science - Recent Advances, New Perspectives and Applications [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.109965.
Повний текст джерелаАнотація:
The presence of plasma density gradient is one of the main sources of Rayleigh–Taylor instability (RTI). The Rayleigh–Taylor instability has application in meteorology to explain cloud formations and in astrophysics to explain finger formation. It has wide applications in the inertial confinement fusion to determine the yield of the reaction. The aim of the chapter is to discuss the current status of the research related to RTI. The current research related to RTI has been reviewed, and general dispersion relation has been derived under the thermal motion of electron. The perturbed densities of ions and electrons are determined using two fluid approach under the small amplitude of oscillations. The dispersion equation is derived with the help of Poisson’s equation and solved numerically to investigate the effect of various parameters on the growth rate and real frequency. It has been shown that the real frequency increases with plasma density gradient, electron temperature and the wavenumber, but magnetic field has opposite effect on it. On the other hand, the growth rate of instability increases with magnetic field and density gradient, but it decreases with electron temperature and wave number.
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Darrigol, Olivier. "Drag and Lift." In Worlds of Flow, 264–322. Oxford University PressOxford, 2005. http://dx.doi.org/10.1093/oso/9780198568438.003.0007.
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Abstract The problem of the forces that a fluid exerts on a solid body challenged hydrodynamics since d’Alembert’s foundational Essaiof 1752. It only found a quantitative, wide-ranging solution in the first third of the twentieth century, after a few partial successes in the nineteenth century and earlier. The first section of this chapter is devoted to these older attempts, including Newton’s molecular-impact theory, Rayleigh’s dead-water theory, and eddy-resistance theories by Poncelet and Saint-Venant. None of these theories truly succeeded in making quantitative predictions, and they all lacked a solid conceptual basis. Newton’s theory artificially neglected the mutual action of fluid molecules, Rayleigh’s implied an absurdly large wake, and Saint-Venant’s required some observational input. Yet they all contained important elements of the modern understanding of fluid resistance. Newton understood how a similitude argument constrained inertial resistance to be quadratic. Rayleigh’s theory foreshadowed the separation process now admitted for non-streamlined flow. Saint-Venant correctly described the eddy resistance resulting from the instability of separated flow. Section 7.2 is devoted to ship resistance. The development of steam navigation in the Victorian empire motivated the efforts of a few learned engineers to reflect on the optimal shape of ship hulls. John Scott Russell saw how to minimize wave resistance. William Rankine clearly distinguished skin friction, large-eddy resistance, and wave resistance. Lastly, and most importantly, William Froude expressed the conditions for a rational use of models and developed the relevant experimental techniques. In his analysis of skin friction, he finely described what Prandtl later called a turbulent boundary layer. His and Rankine’s insights into the mechanisms of high-Reynolds-number resistance nevertheless remained qualitative. The means were still lacking to turn them into efficient computational schemes.
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Zhulay, Yuriy, and Olexiy Nikolayev. "Sonic Drilling with Use of a Cavitation Hydraulic Vibrator." In Mining Technology [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.100336.
Повний текст джерелаАнотація:
Sonic drilling is a soil penetration technique that strongly reduces friction on the drill string and drill bit due to liquefaction, inertia effects and a temporary reduction of porosity of the soil. Modern studies to assess the effect of the vibration frequency of the drill bit on the rock fragmentation in experimental and theoretical works on drilling various rocks by the sonic method have shown that vibration frequencies of ~ 1.4 kHz are the most beneficial for ensuring the maximum drilling speed in hard rocks. The above frequencies of excitation of vibrations of the drill bit can be achieved by using a cavitation hydrovibrator. The cavitation hydrovibrator is the Venturi tube of special geometry that converts a stationary fluid (flushing mud) flow into an oscillatory stalling cavitation flow and hydrovibrator structure longitudinal vibrations. The drill bit vibration accelerations are realized in such a drill string, leading to the destruction of rock. Efficient removal of rock particles from the bottomhole is achieved due to high-frequency shock self-oscillations of mud pressure exceeding the steady-state pressure at the generator inlet. The cavitation hydraulic vibrator lacks the main disadvantages of submersible hydraulic hammers.
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Khoddami Maraghi, Zahra. "Vibration and Instability of Smart-Composite Sandwich Structure: Flutter and Divergences." In Vibration Engineering - Analysis, Control, and Utilization [Working Title]. IntechOpen, 2025. https://doi.org/10.5772/intechopen.1009143.
Повний текст джерелаАнотація:
This study presents a comprehensive analysis of the vibration and instability characteristics of smart sandwich structures, focusing on beams, circular plates, and square plates with magnetorheological fluid (MRF) cores and magnetostrictive (Ms) skins. Timoshenko beam theory is applied to model the beam structures, accounting for both shear deformation and rotational inertia, while classical plate theory is used for the plate structures to capture the rheology behavior. The energy method is applied to derive the system’s potential and kinetic energy, which are essential for evaluating the stability and vibration characteristics, and the differential quadrature method (DQM) is employed to solve the governing equations numerically. The research investigates the impact of magnetic fields on the natural frequency, loss factor, and system stability using several MRF models. Geometric parameters, including core and skin thickness, significantly affected the natural frequency and damping behavior, identifying flutter and divergences phenomena. The study also introduces a velocity feedback control parameter (Kvfc), which demonstrated an opposing effect on magnetic fields by enhancing damping and reducing the natural frequency. The research provides valuable insights for optimizing vibration control and stability in MRF-based sandwich structures.
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Harrison, Roger G., Paul W. Todd, Scott R. Rudge, and Demetri P. Petrides. "Sedimentation." In Bioseparations Science and Engineering. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780195391817.003.0008.
Повний текст джерелаАнотація:
Sedimentation is the movement of particles or macromolecules in an inertial field. Its applications in separation technology are extremely widespread. Extremes of applications range from the settling due to gravity of tons of solid waste and bacteria in wastewater treatment plants to the centrifugation of a few microliters of blood to determine packed blood cell volume (“hematocrit”) in the clinical laboratory. Accelerations range from 1 × g in flocculation tanks to 100,000 × g in ultracentrifuges for measuring the sedimentation rates of macromolecules. In bioprocessing, the most frequent applications of sedimentation include the clarification of broths and lysates, the collection of cells and inclusion bodies, and the separation of fluids having different densities. Unit operations in sedimentation include settling tanks and tubular centrifuges for batch processing, continuous centrifuges such as disk centrifuges, and less frequently used unit operations such as field-flow fractionators and inclined settlers. Bench scale centrifuges that accommodate small samples can be found in most research laboratories and are frequently applied to the processing of bench scale cell cultures and enzyme preparations. Certain high-speed ultracentrifuges are used as analytical tools for the estimation of molecular weights and diffusion coefficients. The chapter begins with a description of the basic principles of sedimentation, followed by methods of characterizing laboratory and larger-scale centrifuges. Two important production centrifuges, the tubular bowl centrifuge and the disk-stack centrifuge, are analyzed in detail to give the basis for scale-up. Ultracentrifuges, important for analytical and preparative work, are then analyzed. The effect of flocculation of particles on sedimentation is presented, and sedimentation of particles at low accelerations is discussed. The chapter concludes with a description of centrifugal elutriation.
Тези доповідей конференцій з теми "Effort inertiel du fluide"
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Berrouk, Abdallah Sofiane, and Dominique Laurence. "Stochastic Large Eddy Simulation of Bluff-Body Two-Way-Coupled Gas-Particle Turbulent Flow." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-12006.
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With the steady increase in computing power, there have been numerous efforts to numerically quantify turbulence modulation by inertial particles. However, highly resolving the flow around thousands to millions of particles to get an accurate particle/turbulence interaction has been prohibited by the number of grid points required. Thus, physical models have been developed and “plugged” to well-resolved numerical simulations to render prediction of turbulence modulation tractable. In this work, flow turbulence modulation by dispersed solid particles in a bluff body was studied using two-way-coupled stochastic large eddy simulation. Point-force scheme was used to model the inertial particle back effects on the fluid motion. The fluid velocity field seen by inertial particles was stochastically constructed based on the filtered flow field obtained from well resolved large eddy simulations. For that purpose a Langevin-type stochastic diffusion process was used with the necessary modifications to account for particle inertia, cross-trajectory effects and the two-way coupling. The numerical results regarding mean and turbulence statistics for the fluid phase show a very good agreement with the experimental findings for both low and high mass loadings (22% and 110% respectively). This numerical investigation demonstrates also the ability of the stochastic-LES-particle approach to predict turbulence modification by inertial particles.
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Hamzehlouia, Sina, and Kamran Behdinan. "First Order Perturbation Technique for Squeeze Film Dampers Executing Small Amplitude Circular Centered Orbits With Aero-Engine Application." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65784.
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This work develops inertial expressions for the lubricant pressure distribution and fluid velocity components for squeeze film dampers (SFDs) executing small amplitude circular centered orbits (CCO), by applying a first order perturbation to the fluid equations. For small amplitude motions of the journal center, it is assumed that the fluid convective inertia terms are negligible relative to the unsteady (temporal) inertia terms. Firstly, a first order perturbation is applied to the pressure and velocity components in the flow equations. Subsequently, the flow equations are solved for the zeroth-order (i.e. non-inertial) velocities and the first-order (i.e. inertial) velocities. The velocity components are incorporated into the flow equations to develop separate expressions for the zeroth-order and the first order pressures. Furthermore, the pressure expressions are numerically solved by applying finite difference approximations to the equations. Finally, a simulation model is developed to determine the lubricant pressure distribution and fluid film reaction forces for different damper operating parameters, including Reynold’s number (i.e. inertia effect), journal eccentricity ratio, and bearing slenderness ratio.
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Chen, Chien-Hsin, and Chang-Yi Ding. "Heat Transfer Characteristics and Cooling Performance of Microchannel Heat Sinks With Nanofluids." In ASME 2009 7th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2009. http://dx.doi.org/10.1115/icnmm2009-82079.
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This paper presents a numerical study on the heat transfer characteristics and cooling performance of a microchannel heat sink with water-γAl2O3 nanofluids having different nanoparticle volume fraction. In view of the small dimensions of the microstructures, the microchannel heat sink is modeled as a fluid-saturated porous medium in the simulation. The Forchheimer-Brinkman-extended Darcy equation is used to describe the fluid flow and the two-equation model with thermal dispersion is utilized for heat transfer. Typical results for the temperature distributions of the fin and fluid phase are presented for various values of the inertial force parameter. It is found that the fin temperature distribution is practically not sensitive to the inertial effect, while the fluid temperature distribution and the total thermal resistance change significantly due to the inertial force effect. In general, the effect of fluid inertia is to reduce the total thermal resistance and the temperature difference between the fin and the fluid phase. The total thermal resistances obtained from the present model with inertial effect match well with the available experimental results, whereas the thermal resistance is overestimated as the inertial effect is neglected.
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Xu, Kefan, Guanghui Zhang, Yiken Lu, Jiazhen Han, Zhongwen Huang, and Wenjie Gong. "Combined Effects of Fluid Inertia and Gas Rarefaction on The Performance of Textured Gas Bearings." In ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/gt2024-124993.
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Abstract Considering the significant discretization effort required to describe texture shapes and possible strong fluid recirculation phenomenon in the deep textured area, this paper attempts to solve the above two hurdles by introducing the multigrid method and inertial correction operation. Furthermore, the first-order slip model and perturbation method were adopted to incorporate gas rarefaction and inertia terms in the compressible Reynolds equation. Moreover, the finite difference method and multigrid algorithm were employed to discretize the pressure governing equations and quickly reduce the iterative residuals of linear systems of equations, respectively. The effects of rotational speed, eccentricity, nominal clearance, state of the lubricated surface, and texture parameters on the static performance of gas bearings were studied. On this basis, the CPU time statistics results show that the computing efficiency of multigrid can be increased by more than 46% compared with the traditional direct solution under the same operating parameters. In addition, it is observed that slip flow and fluid inertia usually reduce the predicted load capacity of gas bearings, and the effect of fluid inertia is stronger than that of the slip flow when the rotational speed is high, the clearance is large, and the dimple texture is deep. The above study supports textured foil journal bearings’ rapid and accurate design in the following engineering practices.
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Tian, Weibing Tian, Keliu Wu, Zhangxin Chen, Yanling Gao, Yin Gao, and Jing Li. "Inertial Effect on Spontaneous Oil-Water Imbibition by Molecular Kinetic Theory." In SPE Europec featured at 82nd EAGE Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205171-ms.
Повний текст джерелаАнотація:
Abstract Imbibition is one of the most common physical phenomena in nature, and it plays an important role in enhanced oil recovery, hydrology, and environmental engineering. For the tight reservoirs, the imbibition method has an obvious advantage in fracturing, shut-in, and huff-puff development. Although the current imbibition studies focus on oil recovery, and the inertial effect in imbibition is neglected and its mechanism is also unclear. In this paper, the inertial effect on spontaneous oil-water imbibition at micron-scale is studied by molecular kinetic theory (MKT). The frictional coefficient in the model is a fitted parameter to match the experimental data during the total imbibition process. Then, the simulation of the initial imbibition stage is conducted and the inertial effect on imbibition is identified by the difference between the model considering the inertial effect (CI) and the model neglecting the inertial effect (NI), or by the proportion of inertial force to the total resistance. Results show that (i) with an increase in the water phase viscosity, the inertial effect time shortens, maximum imbibition height and rate decrease, and thus the inertial effect on imbibition weakens; (ii) with an increase in the oil phase viscosity, the inertial effect time changes little, the maximum imbibition height and rate decrease slightly, namely, the inertial effect depends slightly on the oil phase. (iii) with an increase in the capillary wettability (hydrophilicity), the inertial effect time shortens, the maximum imbibition rate first increases and then decreases, and the inertial effect on imbibition weakens. This work sheds light on the inertial effect on oil-water imbibition by MKT, considering the effects of dynamic contact angle, water phase viscosity, oil phase viscosity, and wettabilities, which is helpful to understand the role of inertia in the oil-water or oil-fracturing fluid imbibition process.
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Matsuoka, Taichi, Kazuhiko Hiramoto, Katsuaki Sunakoda, and Naoto Abe. "Variable Inertia Damper Using MR Fluid." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63007.
Повний текст джерелаАнотація:
Inertia damper has an inertia effect by a flywheel which is caused by a quick moving mass. In general, it is difficult to change the inertia mass physically. In order to obtain a variable inertia effect, a new type of inertia damper has a long bypass pipe is proposed in this paper. This type of damper generates a damping effect and inertia effect by the fluid. It is noted that the inertia effect is depended on a density of the fluid, cross sectional areas of cylinder and bypass pipe, and length of the bypass pipe. If the diameter of the bypass pipe can be controlled, it means that a cross sectional area of the bypass pipe can be switched by clustering particles of MR fluid under magnetization, the inertia effect might be artificially controllable. A trial damper with several electromagnets installed along the long bypass pipe is manufactured, and dynamic property is measured when MR fluid inside the bypass pipe is magnetized by the electromagnets. From experimental results, it seems to be that the inertia effect can be switched and depended on amplitude of magnetization. Finally, the calculated results are theoretically approached, and compared with the experimental results.
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Khadrawi, A. F., and M. A. Al-Nimr. "The Effect of the Local Inertial Term on the Free Convection Fluid Flow in Vertical Channels Partially Filled With Porous Media." In ASME 2002 Joint U.S.-European Fluids Engineering Division Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/fedsm2002-31110.
Повний текст джерелаАнотація:
The transient hydrodynamics and thermal behaviors of the free convection fluid flow in open-ended vertical parallel-plate channels partially filled with porous material are investigated. The role of the local macroscopic inertial term in the porous domain momentum equation is studied. It is found that the effect of the local inertial term on the channel behavior is insignificant when the Darcy number is less than 1E−4 for all operating conditions. Also, the effect of the macroscopic inertial term is insignificant at large values of the viscosity ratio >1.0, and over the entire ranges of diffusivity ratio, conductivity ratio, and Prandtl number.
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Hussain, Md Yahia, and Roger E. Khayat. "Effect of Wall Movement on a Jet Depositing on a Moving Wall at Moderate Reynolds Number." In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30731.
Повний текст джерелаАнотація:
The steady flow of a moderately inertial jet depositing on a moving wall, is examined theoretically near channel exit. The free surface jet emerges from a channel and adheres to a wall, which may move in the same or opposite direction to the acting channel pressure gradient. The problem is solved using the method of matched asymptotic expansions. The small parameter involved in the expansions is the inverse Reynolds number. The flow field is obtained as a composite expansion by matching the flow in the boundary layer regions near the free surface, with the flow in the core region. The influence of inertia and wall velocity on the shape of the free surface, the velocity and stress is emphasized. It is found that the viscous relaxation length is essentially uninfluenced by the velocity of a forward moving wall. In contrast, it diminishes rapidly with the velocity of a backward moving wall.
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Matsuoka, Taichi, Naoto Abe, Kazuhiko Hiramoto, and Katsuaki Sunakoda. "Variable Inertia Damper Using MR Fluid: Part II — Improvement of Inertia Effect." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65922.
Повний текст джерелаАнотація:
The authors have developed fluid inertia damper using MR fluid in order to obtain a variable inertia effect. From the experiments, it seemed to be that the inertia effect was slightly switched, but very small. In this paper, to get much inertia effect, the damper was improved by using long bypass pipe of stainless steel, and 24 electromagnets were installed along the long by-pass pipe. Dynamic property was investigated experimentally and theoretically.
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Suara, Kabir, Mohammadreza Khanarmuei, and Richard Brown. "Quantification of inertial effect on the transport of macro-plastics in a tidal embayment." In 22nd Australasian Fluid Mechanics Conference AFMC2020. Brisbane, Australia: The University of Queensland, 2020. http://dx.doi.org/10.14264/8c3ee36.
Повний текст джерела